1. Field of the Invention
The present invention relates generally to automated equipment control using a raster-based database, including vehicle navigation and guidance using global navigation satellite system (GNSS), inertial navigation system (INS) and other positioning inputs, and machine control functions such as variable-rate chemical applications in agricultural spraying.
2. Description of the Related Art
GNSS technology advanced vehicle and machine guidance and control in various technical fields, including the field of agricultural guidance by enabling reliable, accurate systems, which are relatively easy to use. GNSS guidance systems are adapted for displaying directional guidance information to assist operators with manually steering the vehicles. For example, the OUTBACK® steering guidance system, which is available from Hemisphere GPS LLC of Calgary, Alberta, Canada and is covered by U.S. Pat. No. 6,539,303 and No. 6,711,501 (incorporated herein by reference), includes an on-board computer capable of storing various straight-line and curved (“contour”) patterns. An advantage of this system is its ability to retain field-specific cultivating, planting, spraying, fertilizing, harvesting and other patterns in memory. This feature enables operators to accurately retrace such patterns. Another advantage relates to the ability to interrupt operations for subsequent resumption by referring to system-generated logs of previously treated areas. The OUTBACK S steering guidance system, and related product offerings from Hemisphere GPS LLC, utilize “near point search method” technology, which logs GPS-defined positions along swath edges, the nearest of which are located for placing the edge of the next swath against the last.
Another type of GPS guidance utilizes “form line following,” wherein vectors, which can be straight-line (A-B) or curved (contour), are computed based on equipment widths offset from the previously-driven form lines. A disadvantage with this type of system is that initial form lines must be driven and delineated based upon which subsequent form lines must be computed and followed. Significant computer overhead can be occupied with such tasks, whereby trade-offs are required between component costs and system responsiveness.
GNSS vehicle guidance equipment using the above techniques is available as a steering guide with a graphical user interface (GUI) for manually-steered vehicles, and also with an autosteer function for automatically steering the vehicle along all or part of its travel path. Automated systems can also control an agricultural procedure or operation, such as spraying, planting, tilling, harvesting, etc. Examples of such equipment are shown in U.S. Pat. No. 7,142,956, which is incorporated herein by reference. U.S. Patent Application Publication No. 2004/0186644 shows satellite-based vehicle guidance control in straight and contour modes, and is also incorporated herein by reference. U.S. Pat. No. 7,162,348 is incorporated herein by reference and discloses an articulated equipment position control system and method whereby a working component, such as an implement, can be guided independently of a motive component, such as a tractor. The implement can optionally be equipped with its own GNSS antenna and/or receiver for interacting with a tractor-mounted GNSS system.
Ideally crops would be planted in perfectly straight, evenly-spaced rows. Guidance through such fields would consist of following relatively simple straight-line patterns. Such guidance modes are commonly referred to as straight line or “A-B” in reference to the equipment traveling in a straight line from point A to point B in a repeating pattern in order to cover an entire field, which is typically flat and rectangular and therefore efficiently divided into multiple, parallel swaths. However, field conditions in many areas are not suitable for A-B guidance. For example, hilly terrain sometimes requires the formation of constant-elevation terraces.
Guidance systems accommodate such irregular conditions by operating in “contour following” modes consisting of curvilinear tracks defined by multiple GNSS points along which the equipment is guided. Initial planting passes made with manual and visually-guided navigation, which may or may not be supplemented with GNSS navigational aids, can cause crop rows to deviate from straight lines. Accommodating such irregular crop rows in subsequent operations (e.g., spraying and harvesting) may require the equipment to deviate from straight-line passes.
“Tramline” (sometimes referred to as “match tracks”) is another operating mode available with some modern GNSS guidance systems. In tramline operating mode the existing crop rows are relatively well protected because the equipment follows or “matches” the previously-driven passes. The equipment wheels or tracks are thus confined between the crop rows. Machine damage from running over crops is thus avoided, or at least minimized.
Preferably a system embodying an aspect of the present invention would avoid the drawbacks inherent in the previous systems described above and be adaptable to various machine control applications, including variably controlling the output of individual nozzles in agricultural sprayers. In particular, raster (e.g., bitmap) data bases can be used with previously-defined world geodetic systems, such as WGS 84, thereby eliminating overhead-intensive tasks such as continuously running extensive searches for points along the edges of previously-driven swaths or computing form lines.
Heretofore there has not been available a raster-based contour swathing system and method with the advantages and features of the present invention.